Encryption and decryption of files are known processes which provide data security for files. Re-encryption of files involves decrypting the files, using an old key or keys, and then encrypting the decrypted files, using a new key or keys. Rekeying involves applying a new key to encrypt files, either as a re-encryption of previously encrypted files or as a new encryption of previously clear text (also known as plain text), i.e., unencrypted, files. Rekeying could also involve decrypting files to clear text. Rekeying could be called for on a regular basis, for data security, for compliance with regulatory requirements or could be asked for if keys are compromised, among other scenarios. Prior rekey solutions have required lengthy application downtime or a maintenance window to transform the data. Input/output (I/O) operations, such as initiated by user applications, are either shut down or have access denied to files, while the files are being rekeyed during the maintenance window. This downtime adds overhead to information technology (IT) personnel. Sometimes it is not possible to finish rekeying within a specified maintenance window. The downtime or denied access to files is disruptive to the user applications. Therefore, there is a need in the art for a solution which overcomes the drawbacks described above.